1. Field of the Invention
The present invention relates to water tables for use with burning or cutting machines and particularly to such water tables which include work supports which are movable relative to the burning machine and the work.
2. Description of the Prior Art
In burning machines, it is advantageous to maintain the part being cut from the metal workplate in the same plane as the workplate until complete separation is achieved. When the part and the workplate are completely separated, it is desirable to permit the part to drop from the workplate without the edges of the part tipping up and without tearing the part from the workplate. This avoids parts with jagged edges. The shapes of finished parts are infinitely random in size and configuration.
A water table is disclosed in U.S. Pat. No. 4,162,060. The water table has a plurality of frames positioned in an open top area, and the frames include several burning bars on which the metal workplate to be cut is supported. Alternative workplate supports are disclosed in U.S. Pat. No. 4,673,103. These workplate supports comprise equilateral pyramids which are individually distributed over a cutting surface at various points according to the general shape of the finished part to be cut from the workplate.
The prior art workplate supports are in certain circumstances found to be inadequate, particularly when it is desired to maintain the finished part in place until it is completely separated from the workplate by the burning machine and then drop the part. The prior art supports are inherently limited in their ability to conform to the particular size and shape of the finished part. The design of the prior art supports results in occasional tipping of the finished part when separated from the workplate due to uneven weight distribution over the supports. Additionally, uneven weight distribution may cause the edge of a finished part to prematurely tear from the workplate before complete separation of the part by the burning machine, thereby rendering the finished part unusable. This is particularly true when a large, thick part is cut.
In a standard burning machine, the movement of the cutting torch is determined by computer directed controls well known to those skilled in the art. The cutting torch is moved relative to the workplate and the water table in both the X and Y directions to create a cutting path which defines the shape of the finished part. The actual burning machine is usually carried on a cutting gantry and is located in a plane directly above the water table. In order to eliminate support problems inherent in the prior art, it has been found desirable to support the workplate by means which are coordinated with the movement of the burning machine and which include members which are suspended from gantries located above the workplate and retractable members located below the workplate. It is desirable to independently control these plate support members while at the same time having the capability to move them in relation to the movement of the burning machine.
Accordingly, it is an object of the present invention to provide a workplate support arrangement for use with a burning machine which may be positioned to provide optimum support from both above and below while a part is being cut from the workplate. A further object of the present invention is to provide means for simultaneously releasing the work support members from the finished part after cutting is completed to avoid undesirable tipping or tearing.